Uncut carbon steerers and bicycle fork failure

spacers above the stem of bike

Have you ever ridden with someone who rides a bike with a whole lot of spacers above his or her stem? Looks hideous, does it not? You might be blushing, because that person could be you. Don’t worry, I am not here to have a go at you about what your bike looks like. In fact, I could not care less. You could have the most old school run of the mill commuter bike for all I care, as long as you are riding a bike you get a thumbs up from me! What I do care about is the safety of a bike – that is what this is about.

Note: If you have an aluminum steerer then the information given below does not apply to you, but you could take note of it for future reference.

If you plan on using spacers above your stem, then you need to make sure that you have a long steerer plug (also called a “compression plug”). A steerer plug fits into the top of your bicycle steerer and protects it from the crushing force created by tightening stem bolts. Every bike will come with a custom steerer plug, but the custom plugs are shallow. This is why bike manufacturers do not recommend that you use spacers above your bicycle stem. Instead what you can do, is you can buy a long steerer plug or cut the steerer above your stem.

PREVIOUS POST: What to look for when buying a second-hand road bike.

1. Buying a long steerer/compression plug

It is important that your steerer plug extends past the lowest of the stem bolts. Most custom steerer plugs will not do this, if you are using spacers above your stem. Using spacers above your stem with a custom (shallow) steerer plug is an accident waiting to happen. It might not happen in the first 1 000km of riding and it might not happen in the first 10 000km, but you are taking a big unnecessary risk. I always point this out when I am riding with someone who is using an uncut carbon steerer. I know that 99% of the time they are not aware of the problem and therefore will definitely not have thought about buying a long steerer plug.

A steerer/compression plug is very cheap. It only costs $10-20 and you can buy it from numerous online stores. I bought one from Merlin Cycles just the other day.

bicycle compression plug

2. Cutting your carbon steerer

As I mentioned above, alternatively you can cut your carbon steerer. A big reason why people do not want to do this is because it will decrease the re-sale value of the bike. If you cut your bicycle steerer and you want to sell your bike on the second-hand bike market in the future, a potential buyer may complain that he or she cannot move the stem further up. This year alone I have sold two second-hand road bikes with the steerers completely cut. I made it very clear to the buyers that if they want the stem to be higher up, then they will have to buy a stem with some rise in it or get a new fork entirely. Neither of them seemed to mind much. With that said, I can imagine it has happened that someone refused to buy a bike, because the carbon steerer is cut. If I wanted to buy a bike and I saw the steerer was cut, I would use that fact to bargain the price down, even if I was not bothered by it.

slammed bike stem

If you are using more than one spacer below your stem, then it could be convenient to cut your steerer and not buy a long steerer plug. If you plan on having NO spacers below your stem, like you see on the bikes of professional cyclist, then I would recommend that you buy a long steerer plug that extends past the lowest of the stem bolts, instead of cutting your steerer. Again, this is so that the future owner of the bike is able to adjust the stem of the bike to the height he or she wants, without having to buy a new fork entirely.

If you want to know more about this topic, just search “carbon steerer failures” on YouTube or Google. It is an interesting topic, that I think most people should know more about.

It is important to note that even if you do not run an uncut carbon steerer, it is still a good idea to drop your fork out every 5 000km or so and inspect it for any damage. It only takes 5-10 minutes and will put your mind at ease knowing your carbon fork is safe to ride. If you do not know how to do this yourself, you can find tutorials for it on YouTube or take it to your local bike shop.

Leave a Reply